// JavaScript Document
	/*
	 * Tween.js
	 * t: current time（当前时间）
	 * b: beginning value（初始值）
	 * c: change in value（变化量）
	 * d: duration（持续时间）
	*/
define(function(require) {
		var Tween = {
			Linear: function(t, b, c, d) { return c*t/d + b; },
			Quad: {
				easeIn: function(t, b, c, d) {
					return c * (t /= d) * t + b;
				},
				easeOut: function(t, b, c, d) {
					return -c *(t /= d)*(t-2) + b;
				},
				easeInOut: function(t, b, c, d) {
					if ((t /= d / 2) < 1) return c / 2 * t * t + b;
					return -c / 2 * ((--t) * (t-2) - 1) + b;
				}
			},
			Cubic: {
				easeIn: function(t, b, c, d) {
					return c * (t /= d) * t * t + b;
				},
				easeOut: function(t, b, c, d) {
					return c * ((t = t/d - 1) * t * t + 1) + b;
				},
				easeInOut: function(t, b, c, d) {
					if ((t /= d / 2) < 1) return c / 2 * t * t*t + b;
					return c / 2*((t -= 2) * t * t + 2) + b;
				}
			},
			Quart: {
				easeIn: function(t, b, c, d) {
					return c * (t /= d) * t * t*t + b;
				},
				easeOut: function(t, b, c, d) {
					return -c * ((t = t/d - 1) * t * t*t - 1) + b;
				},
				easeInOut: function(t, b, c, d) {
					if ((t /= d / 2) < 1) return c / 2 * t * t * t * t + b;
					return -c / 2 * ((t -= 2) * t * t*t - 2) + b;
				}
			},
			Quint: {
				easeIn: function(t, b, c, d) {
					return c * (t /= d) * t * t * t * t + b;
				},
				easeOut: function(t, b, c, d) {
					return c * ((t = t/d - 1) * t * t * t * t + 1) + b;
				},
				easeInOut: function(t, b, c, d) {
					if ((t /= d / 2) < 1) return c / 2 * t * t * t * t * t + b;
					return c / 2*((t -= 2) * t * t * t * t + 2) + b;
				}
			},
			Sine: {
				easeIn: function(t, b, c, d) {
					return -c * Math.cos(t/d * (Math.PI/2)) + c + b;
				},
				easeOut: function(t, b, c, d) {
					return c * Math.sin(t/d * (Math.PI/2)) + b;
				},
				easeInOut: function(t, b, c, d) {
					return -c / 2 * (Math.cos(Math.PI * t/d) - 1) + b;
				}
			},
			Expo: {
				easeIn: function(t, b, c, d) {
					return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b;
				},
				easeOut: function(t, b, c, d) {
					return (t==d) ? b + c : c * (-Math.pow(2, -10 * t/d) + 1) + b;
				},
				easeInOut: function(t, b, c, d) {
					if (t==0) return b;
					if (t==d) return b+c;
					if ((t /= d / 2) < 1) return c / 2 * Math.pow(2, 10 * (t - 1)) + b;
					return c / 2 * (-Math.pow(2, -10 * --t) + 2) + b;
				}
			},
			Circ: {
				easeIn: function(t, b, c, d) {
					return -c * (Math.sqrt(1 - (t /= d) * t) - 1) + b;
				},
				easeOut: function(t, b, c, d) {
					return c * Math.sqrt(1 - (t = t/d - 1) * t) + b;
				},
				easeInOut: function(t, b, c, d) {
					if ((t /= d / 2) < 1) return -c / 2 * (Math.sqrt(1 - t * t) - 1) + b;
					return c / 2 * (Math.sqrt(1 - (t -= 2) * t) + 1) + b;
				}
			},
			Elastic: {
				easeIn: function(t, b, c, d, a, p) {
					var s;
					if (t==0) return b;
					if ((t /= d) == 1) return b + c;
					if (typeof p == "undefined") p = d * .3;
					if (!a || a < Math.abs(c)) {
						s = p / 4;
						a = c;
					} else {
						s = p / (2 * Math.PI) * Math.asin(c / a);
					}
					return -(a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;
				},
				easeOut: function(t, b, c, d, a, p) {
					var s;
					if (t==0) return b;
					if ((t /= d) == 1) return b + c;
					if (typeof p == "undefined") p = d * .3;
					if (!a || a < Math.abs(c)) {
						a = c; 
						s = p / 4;
					} else {
						s = p/(2*Math.PI) * Math.asin(c/a);
					}
					return (a * Math.pow(2, -10 * t) * Math.sin((t * d - s) * (2 * Math.PI) / p) + c + b);
				},
				easeInOut: function(t, b, c, d, a, p) {
					var s;
					if (t==0) return b;
					if ((t /= d / 2) == 2) return b+c;
					if (typeof p == "undefined") p = d * (.3 * 1.5);
					if (!a || a < Math.abs(c)) {
						a = c; 
						s = p / 4;
					} else {
						s = p / (2  *Math.PI) * Math.asin(c / a);
					}
					if (t < 1) return -.5 * (a * Math.pow(2, 10* (t -=1 )) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;
					return a * Math.pow(2, -10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p ) * .5 + c + b;
				}
			},
			Back: {
				easeIn: function(t, b, c, d, s) {
					if (typeof s == "undefined") s = 1.70158;
					return c * (t /= d) * t * ((s + 1) * t - s) + b;
				},
				easeOut: function(t, b, c, d, s) {
					if (typeof s == "undefined") s = 1.70158;
					return c * ((t = t/d - 1) * t * ((s + 1) * t + s) + 1) + b;
				},
				easeInOut: function(t, b, c, d, s) {
					if (typeof s == "undefined") s = 1.70158; 
					if ((t /= d / 2) < 1) return c / 2 * (t * t * (((s *= (1.525)) + 1) * t - s)) + b;
					return c / 2*((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2) + b;
				}
			},
			Bounce: {
				easeIn: function(t, b, c, d) {
					return c - Tween.Bounce.easeOut(d-t, 0, c, d) + b;
				},
				easeOut: function(t, b, c, d) {
					if ((t /= d) < (1 / 2.75)) {
						return c * (7.5625 * t * t) + b;
					} else if (t < (2 / 2.75)) {
						return c * (7.5625 * (t -= (1.5 / 2.75)) * t + .75) + b;
					} else if (t < (2.5 / 2.75)) {
						return c * (7.5625 * (t -= (2.25 / 2.75)) * t + .9375) + b;
					} else {
						return c * (7.5625 * (t -= (2.625 / 2.75)) * t + .984375) + b;
					}
				},
				easeInOut: function(t, b, c, d) {
					if (t < d / 2) {
						return Tween.Bounce.easeIn(t * 2, 0, c, d) * .5 + b;
					} else {
						return Tween.Bounce.easeOut(t * 2 - d, 0, c, d) * .5 + c * .5 + b;
					}
				}
			}
		}
	return Tween;
});